Патент USA US2069471код для вставки
Feb. 2, 1937. ‘ D. J. BAKER ANTIFRICT ION SCREW ‘Filed June 19, 1936 2,069,471 2 Sheets-Sheet 1 \DOWJBMG’IT. 2,069,471 Patented Feb. 2, 1931 UNITED STATES PATENT OFFICE 2,069,471 ANTIFRICTION SCREW Donald J. Baker, Pasadena, Calif. Application sum 19, 1936, Serial No. 86,188 10 Claims. This invention relates to a screw and nut assembly and in particular to constructions em ploying ball and/or roller bearings for reducing 5 1 UK the friction between a screw and a cooperating nut. A general object of the invention is to devise an improved construction of ball-bearing or roller-bearing screws for carrying greater loads. A speci?c object of the invention is to devise an improved retainer o-r cage for the anti-friction bearings which takes up very little space between the screw and the nut. A further object is to devise an improved thread construction in the nut and screw assembly which will permit the ball or roller races on both the screw and the nut to be formed by grinding operations. The constructions of my invention are capable of general use in “any situation where screws are useful, such as in lifting jacks, pumps, presses and the like. My invention is illustrated in the drawings in which: (Cl. 74-459) vided with a. helical thread 4 of the same pitch as the screw thread 2, and this thread is pref erably formed with a lower side 4a. arranged at 45 degrees to the axis of the thread or parallel with the upper face 20. of the screw thread 2, and a ball race 4b is formed along the upper edge of the thread 4. The ball race 4b is also prefer ably formed as the arc of a quarter-circle and is transversely inclined to the axis of the nut by an angle of 45 degrees. 10 The screw l is supported within the nut 3 by ‘ means of a series of balls 5 which are arranged about the screw and are seated in the ball-race 4b formed on the thread of the nut and engage the ball-race 2b formed on the thread of the 15 screw. The balls 5 are maintained in proper spaced relation by a retainer or cage 6 which is preferably formed as a shell-like member hav ing a threaded exterior and a threaded interior of the same pitch as the nut and screw threads 20 and having a shape closely conforming with‘the threads on the nut and the screw. As will be seen from Figure l, the upper end of the retainer comprising the three upper convolutions of the thread is shown in elevation, while the lower por 25 tion is shown in section. The retainer is prefer Figure l is a view showing one arrangement of ball-bearing screw and nut assembly in side ele vation with parts of the assembly shown in sec 25 tion; ' ably formed of two helical walls 6a and 6b ar Figure 2 is an enlarged fragmentary sectional ranged at right angles to each‘ other and each view taken along line 2-—2 of Figure 1; '_ being transversely) inclined at an angle of 45 de Figure 3 is an. enlarged detailed view showing grees to the axis of the screw. The wall 6b is 30 the manner of mounting a ball in the ball re-x of su?icient thickness to serve as a carrier for 30 tainer; the balls 5, while the walls 6a may be reduced in , Figure 4 is a fragmentary View, partly in sec section to a thickness su?icient only to give the tion and partly in elevation, showing another required strength or rigidity to the retainer. arrangement of ball bearing screw and'nut as ' The retainer 6 may be formed by die-casting, or sembly in which ball races are provided on both it may be formed from solid or tubular stock by 35 sides of the screw thread;v ' machining the thread-like outer and inner sur Figure 5 is a fragmentary enlarged sectional faces on a lathe, or, if desired, the retainer may view showing a modi?ed method of mounting the be formed by two separate helical strips, one balls in the retainer; _ forming the wall 6a. and the other forming the 40 Figure 6 is a fragmentary view, partly in sec wall 61), and the two being suitably joined to 40 tion and partly in elevation, illustrating a nut gether as by welding along the edges. If desired, and screw assembly employing roller bearings; the retainer may be formed of a single helical strip formed in the shape of wall 6b, and. for the and Figure 7 is a fragmentary vertical sectional purpose of re-enforclng the retainer, jumper 45 view showing a modi?ed arrangement of roller strips may be secured across adjacent edges of 45 bearings on each side of the threads of the adjacent convolutions of the strip. nut and screw. . ' One method of mounting the balls in the re Referring to Figure 1 the screw I is provided _ tainer 6 is illustrated in Figure ;3. First, the holes with a helical thread 2 formed thereon, the upper for? receiving the balls are formed by drilling side 2a of the thread being preferably formed at - through the thick wall 6b from the outside of 50 an angle of 45 degrees to the axis of the shaft, the retainer, and the drilling operation is stopped and the lower face of the thread having a ball before the drill passes entirely through the wall race 2b formed thereon, the race being prefer so as to leave a tapered shoulder Be at the bottom . ably formed as one quarter of the arc of the cir of the hole. The drill is large enough to afford cle and being transversely inclined at an angle 55 of 45 degrees to the axis of the screw. The axial adequate clearance f or the ball 5, and the shoulder 60 prevents the ball from passing through the contour of the thread on the screw is shown hole. After the balls are placed in the holes of at the bottom of the screw in the cross-hatched the. retainer, a retaining shoulder 6d similar to area marker Ila. The nut which cooperates with shoulder to is formed around the edge of the hole 60 the screw is indicated at 3 in section and-is pro» 2 2,069,471 at the other face of the wall 6b in any desired manner, as by a suitable swaging tool. The in dentation formed by the swaging tool is shown at Se in Figure 3. Any other suitable method of retaining the balls in the holes may be employed. The enlarged sectional view shown in Figure 2 illustrates the arrangement of the balls in the. tures in any suitable manner as by pins 9 sup ported in the wall 67) and freely passing through the rollers 8. The rollers 8 may be cylindrical in shape, but in order to obtain better rolling action I prefer to form them in a frusto-conical shape, with the apex of the generating cone located sub stantially on the axis of the screw. retainer along the axis of the thread. The balls ' In order to provide a lateral bearing surface and may be spaced apart any desired distance con prevent lateral shifting of the screw, a shoulder sistent with the load to be carried. It will be 20 may be formed on the inneryedge of the race understood that the closer the spacing the greater 2b and a similar shoulder 4c may be formed on 10 the allowable load which can be carried by the the inner edge of the race 4b and these two shoul screw, and the only limit to the closeness of ders cooperate with the opposing ends of the roll spacing is the reduction of the material of the ,ers 8 to prevent excessive lateral play between 15 retainer between the balls to a point to weaken the screw and the nut. 15 the retainer. In Figure 7 I have illustrated a fourth modi As will be understood by those skilled in the ?cation of a nut and screw assembly, and this art, the nut may be held stationary and the screw arrangement corresponds to the arrangement rotated, or vice versa. In any case, the retainer shown in Figure 4 except that roller bearings are 20 8 is free to rotate, and will rotate at half the speed of the rotary element and will advance at half theaxial speed as the movable element. Ac cordingly, in designing a screw according to my invention, in order that the race on the nut thread 25 shall be completely ?lled with balls or rollers at all times, the retainer should have a length equal to one-half of the distance of travel of the mov able element plus the length of the nut. In Figure 4, I have shown a modi?ed construc 30 tion similar to that illustrated in Figure 1, and corresponding elements in these two ?gures are indicated by the same reference numerals. In this arrangement ball race 2a’ is formed on the upper surface of the screw thread 2 while the op posing ball race 4a’ is formed on the lower face of the nut thread 4, and a series of balls 5' are arranged between these two races. This con struction also includes the ball races 2b and 4b, with balls 5, the same as in Figure 1. With this arrangement, the nut and screw assembly will withstand a thrust-in either direction along its axis, whereas in the arrangement of Figure 1, axial thrust can be applied in one direction only. The construction of the retainer 6 in Figure 4 is 45 substantially like that shown in Figure 1 in that it is formed mainly of two helical walls arranged at right angles to each other, but ball bearings are supported in each helical wall instead 01' in only one wall. - In Figure 5 I have illustrated amodi?ed ar rangement for mounting the ball hearings in the ' retainer. In this arrangement I have shown the ball 5 as being mounted in a separate metallic insert ‘I which in turn is supported in any suitable 55 manner in holes formed in the retainer wall 6b. By employing a separate metallic retainer for each individual ball, it is possible to first] mount the ball within the retainer 1 separate from the cage retainer 6, and then mount the unit assem bly, including the ball 5 and the retainer 1, within employed instead of ball bearings. As will be 20 seen from the drawings, the bearing retainer ele ment also consists mainly of two helical walls hav ing transverse inclinations of substantially 45 de grees to the axis of the screw and being arranged at right angles to each other. A series of rollers 25 8 are located between two opposing faces of the threads of the nut and screw while a series of rollers 8' are arranged between the two remain ing opposing faces of the threads on the nut and screw. As shown in Figure 7, I prefer to stagger 30 the rollers 8 and 8' in vertical spacing for con venience in mounting the rollers within the re tainer 6. Here also, the rollers are formed with the frusto-conical shape with the apex of the generating cone located substantially on the axis 35 of the screw. From what has been said above, it will be clear that due to the particular construction and ar rangement of the retainer, the retainer takes up very little space between the screw and the nut, 40 and it is, therefore, possible to employ a screw having threads with an outside diameter equal to or greater than the inside diameter of the thread in the nut. This construction offers a greater seating area for the balls and/or rollers and, 45 therefore, a correspondingly greater load carrying capacity of the screw. Also, the particular shape ‘and arrangement of the two ball or roller races provides lateral support for the screw and pre vents wobbling of the screw. Furthermore, by 50 forming the two races at an angle in the manner described, it is possible to grind these races to accurate shape, and this would not be possible in case the races were formed in the side of a thread of square cross-section. It will be understood that 55 the races may be ground to shape by means of a grinding wheel of a smaller diameter than the in side diameter of the thread on the nut and oper ated on a spindle extending into the nut substan tially parallel with the axis of the nut. 60 the cage retainer 6. _ It will be noted that in all forms of my inven In Figure 6 I have illustrated a nut and screw tion disclosed herein, the thread face extends be assembly similar to that shown in Figure 1 but in low the lower edge of the bearing race on the which roller bearings are substituted for ball bear root side of the thread, that is, the bearing race ings. In this arrangement the races 2b and 4b - is spaced from the root of the thread. This con are formed with straight transverse sections ar struction permits the ball retainer to be formed 65 ranged at an angle of substantially 60 degrees to of helical walls of straight transverse sections ar the axis of the screw, and the two thread faces ranged at substantially right angles to each other, 2a and la have substantially straight transverse and it provides sui?cient room for the helical walls 70 sections arranged substantially at right angles to of the retainer to extend beyond the ball races the faces 2b and 4b. The retainer 6 is also formed and to give adequate support for the balls as shown 70 of two helical walls 6a and 6b arranged at right in the various ?gures of the drawings. angles to each other transversely. A series of In the appended claims the terms “rolling hear rollers l are mounted in apertures formed in hell ing elements” and “anti-friction elements” are to TI cal wall ‘D and may be retained in these aper be interpreted broadly to apply to either a ball ele 75 3 . 2,069,471 bearing race formed on one face of said thread, said race being arranged so that its lower edge is ment or a roller element; the term “bearing race” is to be broadly interpreted to apply to a race for spaced from the root of said thre d. . 5. In combination, a screw an a cooperating either a ball or a roller; the term “complemental” is used to de?ne the relation between the ex terior and interior thead on the retainer whereby nut, each provided with V-shaped threads, and a plurality of roller bearing elements arranged opposing faces of the threads ‘on said transverse angular relations corresponding to the ' between nut and having their axes directed substantially angular relations of the faces of the thread. While I prefer to use a 45 degree relation of the towards the axis ofsaid screw, said opposing 10 two helical walls forming the cylindrical bearing ' thread faces being provided each with a shoulder 10 retainer in Figures 1, 4, and 7, which results in the cooperating with opposing ends of said rollers to two walls being at right angles to each other, it prevent lateral displacement of said screw with respect to the nut. will be understood that this relation is not abso the retainer is formed as two helical walls having 6. A retainer for rolling bearing elements com prising a tubular member formed of a helical 15 wall of uniform thickness and having a trans verse inclination of substantially 45 degrees to the axis of the cylinder and a second helical wall of lute but may be varied somewhat above or below 15 this angle. Also, the axis of the rollers 8 in Fig ure 6 may vary from the 60 degree angular posi tion with respect to the axis of the screw. What I claim is: ' ,_ uniform thickness joining adjacent edges of the 1. In combination, a screw and a cooperating ?rst helical wall and having a. transverse inclina 20 tion of substantially 90 degrees to the first helical wall, one of said helical walls being thicker than the other and being provided with a plurality of spaced holes for receiving and retaining a plu nut, each provided with V-shaped threads, a bearing race formed on one face of the thread of said screw and spaced from the root thereof, a bearing race formed on an opposing face of the thread of said nut and spaced from the root of '7. A ball retainer comprising a tubular‘member having a V-shaped threaded exterior and a threaded interior complemental to the exterior, the walls of said thread being arranged substan tially at right angles to each other and a plu 30 rality of‘ balls supported in a plurality of holes formed in one side-wall of said thread, each of bearing elements in spaced relation, said retainer comprising a tubular member formed of two heli 30 cal walls arranged substantially at right angles to each other transversely thereof, one helical wall being arranged between one pair of opposing said balls being mounted in an individual retainer ring which in turn is supported in a hole formed faces of the threads on the nut and screw and the other helical wall being arranged between the other pair of opposing faces of the threads on the nut and screw, said rolling bearing elements be ing retained in holes formed in one of said helical in said hollow cylinder. _ walls. ranged substantially at right angles to each other 35 8. A retainer for rolling bearing elements com prising a tubular member formed of two helical walls joined along their edges and being ar > 2. In combination, a screw and a cooperating ~10 25 rality of rolling bearing elements. 25 the thread, a plurality of rolling bearing elements arranged in said races, and a retainer located be tween said screw and mat for maintaining said transversely of their length, one of said helical 40 walls being provided with a plurality of holes spaced along the length thereof, a rolling bear~ ing element arranged in each hole, and means for retaining said elements in said holes inde 46 pendently of said screw and nut. 9. In“ combination, a screw and a cooperating nut, each provided with V-shaped threads, the faces of each of said threads being arranged sub stantially at 90 degrees to each other, a bearing race formed on one face of the thread of said screw and spaced from the root thereof, a hear ing race formed on an opposing face of the thread of said nut and spaced from the root of the thread, a plurality of rolling bearing elements nut, each provided with V-shaped threads, the walls of said threads being arranged substantially arranged in said races, and a retainer located be tween said screw and nut for maintaining said at right angles to each other, a plurality of roll bearing elements in spaced relation, said retainer > ing bearing elements arranged between opposing 50 comprising a tubular member having a V-shaped faces of the threads of said nut and screw, a re tainer located between said screw and said nut thread formed on the exteriorthereof and a simi for maintaining said bearing elements in spaced lar thread formed on the interior in complemen tal relation with the exterior thread, whereby said relation, said bearing elements comprising rollers retainer is formed of two helical walls joined along mounted in individual holes formed in said re. 55 their edges, one helical wall being located between tainer, and means for mounting said rollers in one pair of opposing faces of the threads on the said holes with their axes directed towards the screw and‘ nut while the other helical wall is ar axis of said screw. ranged substantially at right angles to the ?rst 10. In combination, a screw and a cooperating helical wall and is located between the other pair nut, each provided with V-shaped threads, the 60 60 of opposing faces of the threads on said screw and walls of said threads being arranged substan tially at right angles to each other, a plurality nut. of rolling bearing elements arranged between op 3. A screw comprising a spindle having a v shaped thread formed thereon with the faces thereof arranged substantially at 90 degrees to posing faces of the threads on said nut and screw, saidbearing elements comprising frusto-com'cal 65 65 each other, and a bearing race formed on one face rollers having the apex of the generating cone located substantially on the axis of the screw, of said thread, said race being arranged so that its lower edge is spaced from the root of said thread. . and a retainer located between said screw and L 4. A nut comprising a hollow member having a V-shaped thread formed within the bore there of, the faces of said thread being arranged sub stantially at 90 degrees to each‘ other, and a nut for maintaining said rollers in spaced rela tion, each of said rollers being rotatably mounted 70 upon a bearing pin passing through the center thereof and secured to said retainer. : J. BAKER.